Patent Application
20100116374
In the field of metal packaging, “easy open” ends for metal cans are well known. Typically, an easy open can end includes a pull tab and an approximately planar panel having a score line defining an opening area. To open a can having an easy open can end, a user may lift a handle of the pull tab to initiate fracture of the score line, and a user may subsequently pull the tab to partially or fully remove a portion of the panel, thereby creating an opening through which a user may access the contents.
Typically, the gap between the pull tab handle and the can end panel is very small. This small gap may make it difficult for a user to grasp the pull tab, because there may not be enough clearance under the pull tab for a user to insert a finger. Therefore, typical easy open cans may be difficult for a user to open.
There is a need for a method of assembling a container including a can end that may allow a user to more easily insert a finger under the pull tab, thereby providing enhanced openability.
A method of forming a container having enhanced openability is disclosed. Such a method may include the steps of: (i) providing a can body; (ii) providing a can end having an approximately planar panel, a pull tab affixed to the panel, and a moveable portion disposed beneath a handle of the tab, the moveable portion being in a first position extending upwardly toward the handle; (iii) filling a comestible product into the can body at an elevated temperature; (iv) seaming the can end to the can body; and (v) moving the moveable portion from the first position to a second position extending downwardly away from the handle, such that a gap is formed or enlarged between the moveable portion and the handle, enhancing accessibility to a user's finger, the moving being in response to internal negative pressure caused by cooling of the product within the can body.
These and various other advantages and features are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there are illustrated and described preferred embodiments of the invention.
Appendix A-1 is a table showing the raw data collected from processing different food products in different types and sizes of containers through different retorts, and determining whether or not the moveable portions 40 toggled to the downward position P2.
Appendix A-2 is a table showing the raw data collected from processing different food products in different types and sizes of containers through different retorts, and determining whether or not the moveable portions 40 toggled to the downward position P2.
Preferred structures and methods for can end technology are described herein. An embodiment of a can end and can that employ this technology are also described. The present invention is not limited to any particular container configuration but rather encompasses use in any container application. Further, the present invention encompasses other can end designs not described herein.
Referring to
Container 10 may be made from any material, for example, steel, aluminum, or tin. Container 10 may contain or be configured to contain a comestible product (not shown), including ready meals, fruits, vegetables, fish, dairy, pet food, a beverage, or any other product that it is desirable to have stored in metal packaging such as container 10. Container 10 may have any length, diameter, wall thickness, and volume. Preferably, container 10 has a standard-sized interior volume that is known in the art for containing a comestible product such as ready meals, fruits, vegetables, fish, dairy, pet food, or a beverage.
Can end 12 may be made from any material, for example, steel, aluminum, or tin. Can end 12 preferably is formed from 0.21 mm gauge DR550N double-reduced steel. In the embodiment shown, can end 12 defines a diameter D1 of 73 mm, although in other embodiments (not shown), can end 12 may define a diameter D1 of any size, including, for example, 83 mm and 99 mm. As shown in
As shown in
When openable panel portion 25 is partially or completely detached from the remainder of panel 20, score 24 and/or openable panel portion 25 define an opening (not shown), through which the comestible product (not shown) may be removed from can body 14. As shown in
As shown in
As shown in
As shown in
As shown in
Moveable portion 40 includes a downwardly inclined annular step 42. As shown in
As shown in
Referring to
When moveable portion 40 is in the up position P1, first gap G1 between pull tab handle 34 and moveable portion 40 may be very small, for example, 2 mm. This relatively small first gap G1 may make it difficult for a user to grasp pull tab handle 34, because there may not be enough clearance under the pull tab for a user to insert a finger. When moveable position 40 is in the down position P2, second gap G2 between pull tab handle 34 and moveable portion 40 may be substantially larger than first gap G1. This larger second gap G2 preferably is large enough to make it easy for a user to grasp pull tab handle 34, because there may be enough clearance under pull tab handle 34 for a user to insert at least part of a finger.
Moveable portion 40 preferably has two stable positions (bi-stable), i.e., the up position P1 (shown in
In order to toggle moveable portion 40 from the up position P1 to the down position P2, a force F may be applied, generally in a downward direction, to moveable portion 40 (as shown in
In some embodiments, it is desirable that can ends 12 be transported to the product-filling facility with moveable portion 40 in the up position P1. While can ends 12 may be formed with moveable portion 40 in either the up position P2 or the down position P2, can ends 12 may be more easily stacked for transportation with moveable portions 40 in the up position P1. For example, in the embodiment shown in
As shown in TABLE 1 (page 8), the presence of annular step 42 in moveable portion 40 may allow moveable portion 40 to stay in the “down” position under a greater variety of post-filling pressure conditions than if annular step 42 was not included. To produce the data shown in TABLE 1, tests were performed using can end 12 designs (with and without annular step 42) having a diameter D1 of 73 mm. Each can end 12 was made of 0.21 mm gauge, double-reduced (DR) tinplate to material specification DR550N. As shown, the presence of annular step 42 may allow container 10 to better withstand impacts and/or high-altitude transportation (at lower ambient pressure) without moveable portion 40 toggling back into the up position P1. If containers 10 are shipped to a high-altitude location, for example, the lower atmospheric pressure may lower the pressure differential across can ends 12, increasing the chance that moveable portions 40 may toggle back into the up position P1. While not being bound by theory, the presence of annular step 42 may increase the pressure differential across the can end 12 that is required to toggle moveable portion 40 back into the up position P1.
As shown in
The retort temperature curve 61 shows the retort starting out at ambient temperature (for example, 25° C.), increasing and being held at a high temperature (which may kill any bacteria in the product 46), and then entering a cool-down period 65, during which the retort drops back down to the ambient temperature. The retort pressure curve 62 shows the retort starting at ambient pressure, increasing and being held at a high pressure (which may allow the product 46 to be heated to a higher temperature without the included water boiling), and then entering an over-pressure period, after which the retort drops back down to the ambient pressure.
The first can pressure curve 63 shows the output of a pressure sensor placed inside of a first container 10. The first can pressure 63 shows the can pressure starting out at ambient pressure (for example, atmospheric pressure), the pressure dropping slightly after the seaming time 67, the pressure increasing while the retort pressure curve 62 is increasing, and the pressure dropping during a low-pressure period 68 that coincides with the cool-down period 65 and the over-pressure period 66.
The second can pressure curve 64 shows the output of a pressure sensor placed inside of a second container 10. The second can pressure 64 shows the can pressure starting out at ambient pressure, the pressure dropping slightly after the seaming time 67, the pressure increasing while the retort pressure curve 62 is increasing (to a lower maximum pressure than the first can pressure curve 63, which may be due to a different amount of headspace 48 or a different initial product 46 temperature), and the pressure dropping during a low-pressure period 68 that coincides with the cool-down period 65 and the over-pressure period 66. The second can pressure curve 64 includes a pressure jump 69, which represents the point where moveable portion 40 toggles from the up position P1 (shown in
As shown in
Before container 10 is seamed at the seaming time 67, a hot product 46 (at an initial equilibrium temperature, for example, of 50-70° C., that is higher than the ambient temperature), which may include a food product and juice or water, is inserted into can body 14. At the seaming time 67, can end 12 is seamed onto can body 14, trapping the hot product 46 (that may contain some steam) into container 10. If the hot product 46 is not sufficiently hot (at an initial equilibrium temperature, for example, of 25-35° C.) to result in a high enough force F acting downward on moveable portion 40 during the cool-down period 65, steam flow closing may be used during the seaming of container 10 to allow sufficient steam to be trapped into container 10 at the seaming time 67.
During the cool-down period 65, container 10 is cooled down, gradually approaching ambient temperature. During the cool-down period 65, the steam that was trapped inside container 10 at the seaming time 67 may be at a lower temperature than the initial temperature at seaming of container 10. This lower temperature and resulting condensation of the steam trapped inside container 10 may result in the low-pressure period 68 being below the initial pressure inside container 10 at the seaming time 67.
In some embodiments, the presence of an over-pressure period 66 may not be required to produce a sufficient pressure differential across can ends 12 to toggle moveable portion 40 to the down position P2. During the cool-down period 65, the steam that may be present in headspace 48 may condense, which may reduce the pressure inside of container 10, as shown in
In some embodiments, during the low-pressure period 68, the combination of the temperature drop during the cool-down period 65 and the high retort pressure during the over-pressure period 66 may both contribute to creating a pressure differential across can ends 12 that results in a force F acting downward on moveable portion 40. In such embodiments, it may be beneficial for toggling of moveable portion 40 to have a over-pressure period 66 during the cool-down period 65. The amount of external pressure in the retort may be correlated to whether or not moveable portion 40 toggles to the down position P2 during cool-down. For example, as shown in
As shown in TABLE 2, data has suggested that when processing a batch of containers 10 of a design that does not include the optional annular step 42, a pressure differential across the can end 12 of at least 500 mbar may result in 100% of the containers 10 having their moveable portions 40 toggled to the down position P2. Data has suggested that when processing a batch of containers 10 of a design that include an annular step 42, a pressure differential across the can end 12 of at least 800 mbar may result in 100% of the containers 10 having their moveable portions 40 toggled to the down position P2. However, as will be discussed below, there are several process variables that may contribute to whether or not a particular set of containers 10 complete processing with their moveable portions 40 toggled to the down position P2, including, but not limited to, the diameter D1 of the can end 12, the type of product 46 contained in container 10, the temperature of product 46 contained in container 10, the length of time during which container 10 is cooled, the external pressure in the retort acting on the outside of can end 12, and headspace 48 (shown in
As shown in TABLE 3, data has suggested that the diameter D1 of can end 12 may be correlated to whether or not moveable portion 40 toggles down to the down position P2 during cool-down following seaming and processing in a retort. TABLE 3 shows data of approximate pressure differentials across can end 12 during hydrostat retort processing that have resulted in enough downward force acting on moveable portion 40 to toggle moveable portion 40 to the down position P2. While not being bound by theory, it is believed that it may take a higher force to toggle moveable portion 40 in the particular designs of can end 12 that have a larger diameter D1, such as 99 mm, compared to a smaller force required to toggle moveable portion 40 to the down position in the designs of can end 12 that have a smaller diameter D1, such as 73 mm.
The degree of cooling while containers 10 are in the over-pressure state in a retort may also be correlated to whether or not moveable portion 40 toggles to the down position P2 during cool-down. While not being bound by theory, it is believed that containers 10 having a can end 12 with a larger diameter D1, such as 99 mm, may retain more heat for a longer period of time than containers 10 having a can end 12 with a smaller diameter D1, such as 73 mm. Therefore, in some designs of can ends 12 having larger diameters D1, the larger diameter containers 10 may not reach a temperature that is close enough to ambient temperature (prior to removal of the over-pressure) to allow enough condensation of steam in the headspace 48 to create a sufficient pressure differential across the can end 12 to toggle moveable portion 40 to the down position P2. For example, if the temperature in container 10 remains relatively high (e.g., 40° C.) before the over-pressure is removed, then there may not be a low enough pressure inside container 10 to toggle the moveable portion. In some embodiments, even if container 10 continues to cool down towards ambient temperature after the over-pressure is removed, the partial vacuum might not be great enough (without the over-pressure) to toggle moveable portion 40 to the down position.
The type of product 46 contained in container 10 and the temperature of the product and juice included in the product 46 may affect whether or not there will be sufficient force during processing to toggle moveable portion 40 from the up position P1 to the down position P2. While not being bound by theory, it is believed that a juice temperature of at least 70° C. may allow sufficient steam to become trapped in container 10 at the time of seaming to allow a sufficient vacuum to develop inside container 10 after container 10 begins to approach ambient temperature (for example, 25° C.). A partial vacuum (i.e., less than atmospheric pressure inside of container 10) may develop in container 10 due to cooling of the steam that was trapped in container 10 at the time of seaming. When the steam at least partially condenses, it takes up less room in container 10 and may create a partial vacuum.
The amount of headspace 48 contained in container 10 between product 46 and can end 12 may affect whether or not there will be sufficient force during processing to toggle moveable portion 40 from the up position P1 to the down position P2. While not being bound by theory, it is believed that a headspace of approximately 5-10 mm may be sufficient to allow moveable portion 40 to toggle to the down position P2 (see Appendices A-1 and A-2 for detailed headspace data and corresponding results). If headspace 48 contained in container 10 at the time of seaming is higher, this may allow a greater amount of steam to be trapped inside container 10 at the time of seaming, which may result in a lower pressure inside container 10 after cooling and condensation of the steam inside container 10. This lower pressure inside container 10 may increase the likelihood that moveable portion 40 will toggle to the down position P2.
In some embodiments, a portion of containers 10 may complete retort processing with moveable portions 40 in the up position P1. In such embodiments, it may be desirable to add a mechanical push-down processing step to mechanically toggle moveable portions 40 that are still in the up position P1 so that moveable portions 40 can be shipped to consumers in the down position P2. For example, in one embodiment, there is a post-retort panel pusher comprising a driven wheel mounted over a slat conveyor (the wheel is driven to match the conveyor speed) that is arranged to push moveable panels 40 down as containers 10 pass under the wheel.
The foregoing description is provided for the purpose of explanation and is not to be construed as limiting the invention. While the invention has been described with reference to preferred embodiments or preferred methods, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Furthermore, although the invention has been described herein with reference to particular structure, methods, and embodiments, the invention is not intended to be limited to the particulars disclosed herein, as the invention extends to all structures, methods and uses that are within the scope of the appended claims. Those skilled in the relevant art, having the benefit of the teachings of this specification, may effect numerous modifications to the invention as described herein, and changes can be made without departing from the scope and spirit of the invention as defined by the appended claims. Furthermore, any features of one described embodiment can be applicable to the other embodiments described herein.
This application claims priority to U.S. Provisional Application No. 61/113,490 filed Nov. 11, 2008, the contents of which are incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61113490 | Nov 2008 | US |
